RNP/Sm antibody test
Quick answer: This blood test looks for antibodies against the combined RNP and Smith protein complex in the cell nucleus. Doctors usually order it when lupus or mixed connective tissue disease is suspected.
- SampleBlood
- TakesAbout 5 minutes
- Before the testNo special preparation is usually needed.
How the test is done
- 1A nurse places a band on your upper arm
- 2The skin over a vein is cleaned
- 3A small needle collects blood into one tube
- 4The lab tests for antibodies to the combined RNP and Sm complex
What your results can mean
Reading your report
A positive result does not by itself confirm a disease, because some healthy people test positive; your doctor reads it with your symptoms and other tests.
If the result is outside the usual range
A positive result can be seen with lupus or mixed connective tissue disease. It is less specific than anti-Smith alone, so doctors usually look at the separate antibodies as well.
Who usually has this test
People with a positive ANA and features suggesting lupus or an overlap connective tissue disease.
Risks and aftercare
Light pressure on the cotton helps prevent a bruise; no other care is needed.
Names and options
Also called: RNP-Sm, anti-RNP/Sm, Sm/RNP
Listed by the hospital as
- RNP - SM ANTIBODY, SERUM
Questions about this test
Why does my report list RNP/Sm separately from Sm?
Some antibodies bind only the Sm protein, while others bind the RNP and Sm complex together. Testing both helps doctors tell lupus apart from mixed connective tissue disease.
Does a positive RNP/Sm mean I have lupus?
Not by itself. It can also be positive in mixed connective tissue disease and other overlap conditions. Your doctor will look at your symptoms and the full antibody pattern.
Is RNP/Sm part of an ANA profile?
Often yes. Many ANA immunoblot panels include it, so you may not need it as a separate test if a profile has been done.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.